The present invention relates to a damper assembly, and more particularly to a temperature responsive valve.
Biasing members known as pneumatic or gas springs, which for convenience can be referred to as counterbalance links, are becoming more common in commercial articles, particularly in the automotive industry, but they are being used in many other fields wherever the need is present to provide a counterbalance force for closure units, such as lids, doors and cabinet fronts, and gas spring replacement for mechanical spring fittings is becoming prevalent. In the automotive field, for example, pneumatic springs are used to assist in opening and supporting trunk lids and lift gates. In such applications, the counterbalance spring assemblies are compressed when the lid is closed, and they extend under differential pressure force acting on the piston when the lid is opened.
In some fields of use, such as automotive, the range of change of the surrounding temperature can be substantial. When the temperature drops, the pressure of the gas within the spring unit drops and concurrently therewith the force holding the piston rod extended or in the hold-open position must drop, and often drops below that required to hold the closure member in an open position. Conversely, at higher temperatures the force is often too high. To counter these disadvantages, pneumatic springs incorporate temperature compensation devices which compensate output force in response temperature changes.
One type of temperature compensation device includes output force modification through selective communication between one or more auxiliary gas chambers with the expansible piston chamber via a temperature responsive valve. The temperature responsive valve commonly includes bushing valves with bi-metal valve discs to provide an increase in gas volume only when the temperature falls below a predetermined value.
Although effective, conventional temperature compensation devices are relatively complex and complicated to manufacture resulting in a relatively expensive component.
Accordingly, it is desirable to provide a gas spring having temperature compensation devices which is effective yet uncomplicated and conducive to uncomplicated manufacture.